Background: Obstetric anesthesia service is peculiar in the practice of anesthesia because the anesthetist has to contend with the presence of two lives (the mother and the fetus) and the influence of changes in maternal physiology resulting from pregnancy. Cesarean section is the most frequently performed surgical procedure in obstetrics. With the increasing rates of cesarean deliveries in both developing and developed world, an audit of the outcome of anesthetic management is paramount to assess the safety of the procedure. Objective: The aim of this article is to audit obstetric anesthesia practice in the University of Ilorin Teaching Hospital (UITH), Ilorin, Nigeria. Methods: The study was a total population study of all obstetric patients who had cesarean delivery at the UITH from January 1, 2010 to December 31, 2014. Results: A total of 14,155 deliveries were recorded from 2010 to 2014 out of which 3908 were cesarean sections giving a cesarean section rate of 27.6%. Ninety percent of the surgeries were emergencies. The most frequent indication for cesarean section was cephalopelvic disproportion (28.7%). Regional anesthesia was used in 92.1% whereas 7.9% had general anesthesia. The most frequent critical incident was hypotension (15.8%). Conclusion: Spinal anesthesia is the most frequently used form of anesthesia for cesarean section.

Obstetric anesthesia services encompass anesthesia for all surgical procedures in the peripartum period including labour analgesia and postoperative pain management. It is peculiar in the practice of anesthesia because the anesthetist has to contend with the presence of two lives (the mother and the fetus) and the influence of changes in maternal physiology resulting from pregnancy.

Cesarean section is the most common performed surgical procedure in obstetrics and certainly one of the most ancient operations in surgery.[1] The use of general anesthesia has drastically fallen in the past few decades because of challenges of difficult airway and poorer fetal outcome.[2] General anesthesia is now used for less than 5% of operative deliveries in the United Kingdom and in the United States.[2] Regional anesthesia that consists of spinal anesthesia, epidural anesthesia, and combined spinal and epidural anesthesia is widely used for obstetric surgical procedures. It is associated with lower maternal blood loss and lower difference between preoperative and postoperative hematocrit.

A study by Imarengiaye et al.[3] showed that spinal anesthesia was the preferred method of anesthesia for cesarean section in tertiary hospitals in Nigeria. General anesthesia was more likely following fetal indications for cesarean section, antepartum hemorrhage, and failed spinal anesthesia. A previous study reported a low utilization of spinal anesthesia during the 1980s and 1990s.[4] However, the trend now favurs a decline in the rates of general anesthesia for cesarean section with an increase in the utilization of spinal anesthesia.[5]

With the changing trend of anesthesia for cesarean deliveries, an audit of obstetric anesthesia practice is paramount to ensure compliance with global best practice. Hence, the aim of this study is to audit obstetric anesthesia in our hospital over a 5-year period.

Materials and methods

The study was approved by the UITH, Ilorin, Nigeria, Ethical Board. It was a retrospective study of all obstetric patients who had cesarean delivery at the UITH from January 1, 2010 to December 31, 2014. The hospital is a tertiary health care center located in the north-central region of Nigeria. It receives patients from Kwara State as well as Kogi, Niger, Ekiti, Osun, and Oyo States. It is a multispecialty hospital providing specialist care in Neurosurgery, Cardiothoracic Surgery, Orthopaedic Surgery, Obstetrics and Gynaecology, Paediatrics, and Internal Medicine, as well as other areas of specialty. It has a total space of 600 beds.

The Obstetric Unit of the hospital is housed in a two-storey building with a total space of 128 beds. It consists of antenatal and postnatal wards that have 30 beds each, a 25-bed postnatal surgical ward, an 18-bedded emergency ward, and a 25-bed gynecology ward. There are antenatal clinics, labor ward, ultrasound room, family planning unit, an operating theater with two functional suites, and a neonatal intensive care unit adjoining the labor ward. The Obstetrics and Gynaecology Department has four firms that are run by consultants who supervise the resident doctors and interns. In 2013, there were 2895 total deliveries with 730 cesarean sections giving a cesarean section rate of 25.2%.

A list of all obstetric patients who had obstetric surgical procedures was compiled from the operating theater register; thereafter, the case files were retrieved from the medical records department of the hospital for analysis.

The inclusion criteria were all obstetric patients who had obstetric surgical procedures during pregnancy, delivery, or within 42 days of its termination and availability of case files for review. Obstetric patients without case records and those who had nonobstetric surgeries were excluded. The data obtained included age, indication for surgery, anesthetic technique, anesthetic complications, and maternal and fetal outcome.

Data analysis

Results generated from this study were expressed as frequencies or proportions of total, means, and standard deviations. Tests of significance were analyzed with Student’s t-test for means. Chi-square test was used for categorical variables using the computer, software package SPSS version 20.0 (Chicago, Illinois. Inc). A P value of less than 0.05 was considered statistically significant.

Results

A total of 14,155 deliveries were recorded from 2010 to 2014 out of which 3908 were cesarean sections giving a cesarean section rate of 27.6%. Seventeen (0.4%) patients were less than 15 years of age whereas 2512 (64.3%) were between the ages of 26 and 35 years [Table 1]. The most frequent indication for cesarean section was cephalopelvic disproportion (28.7%). Other common indications were previous cesarean scars (19.3%) and preeclampsia/eclampsia (19.2%) [Table 2]. Emergency cesarean sections accounted for 3511 (89.8%) of the cases.

Of the 3908 cesarean sections, regional anesthesia was used for 3598 (92.07%) whereas general anesthesia was used in 310 (7.93%) surgeries. The regional anesthesia techniques employed were subarachnoid block (SAB) in 3556 (91%) of all cesarean sections and epidural anesthesia in 42 (1.09%). Although regional anesthesia was the most frequently used anesthetic technique, general anesthesia was statistically more likely to be used in emergency cesarean section than in elective procedures (P < 0.05) [Table 3]. No abdominal delivery was done using combined spinal epidural anesthesia.

Three thousand nine hundred thirty-one babies were delivered by cesarean section, out of which 304 (7.7%) required admission in the neonatal intensive care unit whereas 140 (3.6%) were stillbirths [Table 3]. The APGAR scores could not be retrieved from the records.

Complications

The critical incidents noted were hypotension in 618 (15.8%) women, cardiac arrest in 11 (0.28%), and death on the table in five (0.13%). The cases that sustained cardiac arrest were from hypotension complicating SAB. Five of these patients subsequently died on the operating table whereas six were resuscitated and discharged. Of the 3556 SABs that were done, 36 (1.0%) failed. None of the epidural anesthesia techniques failed.

Discussion

Our study showed that SAB remained the most frequently used technique of anesthesia for cesarean section over the 5 years with 91% of the total cases performed using SAB. Epidural anesthesia is still only used sparingly (1%) as compared to a rate of 26% in the United Kingdom.[6] SAB provides a better quality of block, is faster in onset, and cheaper than epidural anesthesia making it more likely to be used. Also, epidural analgesia service in labor is not yet properly established due to inadequate manpower. Parturients who have been receiving epidural analgesia in labor are more likely to have epidural anesthesia if a cesarean section becomes necessary as the epidural catheter is already in place making the administration of anesthesia easier. This probably also explains the low rate of combined spinal and epidural anesthesia.

Studies have shown that health institutions that previously preferred general anesthesia for cesarean deliveries are now transitioning to regional techniques.[4],[7] Challenges of difficult airway, aspiration pneumonitis, and fetal depression have made general anesthesia undesirable for most cesarean sections.

There was a 1% failure rate when epidural anesthesia was used. Other tertiary institutions reported a rate of 6% to 9.1%.[8],[9] While this may be acceptably low, the reluctance of anesthetists to report failures in anesthetic technique cannot be ruled out. Cook et al.[10] found that only 25% of critical incidents were reported in a study of major airway complications. Kinsella[6] found that the rate of failure to achieve a pain-free cesarean section operation was 6% with spinals and 24% with epidural top-up.

The critical incidents experienced by the patients were hypotension (15.8%), cardiac arrest that was resuscitated with return of spontaneous circulation (0.28%), and death on the table (0.13%). Hypotension is a recognized complication of SAB. As this technique was used in 91% of the operations, the rate of hypotension in this study is understandable. Regional anesthesia has been found to have a lower rate of serious side effects when compared to general anesthesia. The cardiac arrest incidences were from uncontrolled hypotension. Despite the fact that most of the procedures are done in conscious patients using spinal anesthesia, standard monitoring and efficient methods to prevent or correct hypotension must not be compromised to prevent morbidity and mortality.

We found that 90% of the cesarean sections were emergency surgical procedures. This may reflect the reluctance of Nigerian women to accept cesarean section except when there is a threat to the life of the mother or baby. Aziken et al.[11] found that only 6.1% of women were willing to accept cesarean section as a method of delivery whereas 81% would accept it if there was a threat to the mother or baby.

Recommendations

We recommend that spinal anesthesia should be the anesthetic technique of choice during cesarean deliveries. The anesthetist should, however, be aware of the frequent complication of hypotension that often requires urgent correction.

Conclusion

Spinal anesthesia is the most frequently used form of anesthesia for cesarean delivery in our hospital. It is a safe and effective method of anesthesia with very few complications.

Acknowledgements

The authors acknowledge the management of the University of Ilorin Teaching Hospital for granting approval for the study and the staff of the surgical wards for their cooperation.

Cook TM, Woodall N, Frerk CO. Major complications of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society.Part 1: anaesthesia. Br J Anaesth 2011;106:617-31.